deepbluejh

I'm no expert, but this is my thought as well. For fuel economy reasons, I regularly let my Celica "drift" up to redlights and stop signs. Sometimes this means taking it out of gear at 70mph on the freeway and letting it drift up an off-ramp to a stop at the top. The car is 10years old with 180k miles and has always run flawlessly.

If for some reason the S2000 is different, then I'd love to hear why.

deepbluejh

You use more gas by leaving it in gear as you brake. You do enhance braking though. IMO, it's a zero-sum trade off.

crank

while the engine is no longer injecting fuel no combustion is takin place, however the pistons are still moving air and create a vaccume...this air helps cool the engine as well as the engine oil since. Heat travels from Hot to cold. Basically, during deceleration the only heat being generated is friction heat since NO fuel is being injected and ignited. am i right ?? lol

crank

during deceleration ZERO fuel is being injected into the combustion chamber read my post above. you actually use less fuel and have more effective breaking since the drivetrain is engaged.

crank

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w00t692

i can't beleive people think the car uses gas when it's engine braking...

that is funny.

Saki GT

Engine specific details aside, always keep your car in gear at speed. The last thing you want to do is be in a situation where you need to gas the car and have your drivetrain disconnected, plus there's risk of car imbalance, wheel lock and breaking the drivetrain by doing something stupid like shifting into the wrong gear from idle rpm, plus all modern cars with ECUs these days cut fuel so long as the engine is still running on kinetic energy (the wheels) you save gas.

There's just no reason to coast in neutral.

Presto123

I coast in neutral to stop all the time. Not at 100MPH, but when coming to a red light I see no reason to leave it in gear. If the light turns green before I stop I'll revmatch into the appropriate gear. Not a big deal really..

Chris S2K

When there's sufficient space behind me and the next car, I coast upon exiting the highway or seeing a yellow/red traffic light coming up. From my rudimentary understanding of automobiles, I don't think it matters much as long as you properly rev match back to engage the drivetrain, although rev matching at high speeds carries greater risk of damage to the drivetrain if it's not properly executed.

It's give and take regarding the cost of coasting vs. engine braking. While engine braking uses zero fuel, it also slows you down much faster than coasting so you may end up having to get back on the gas pedal. I imagine it's probably a wash, but you'd probably wear the engine out more by engine braking.

Enlighten me if there is something I'm missing here.

JackS

In gear, in control. Out of gear, out of control.
My advice- Stay in control of your car when it's moving.